Yeh, all you need is a gun that's got good trigger response and is sighted in accurately. Those are the most important two aspects for guns at TTAC. There are nights where you're encouraged to wear civvie clothes, and you'll often see guys running around in t-shirts, despite being adults who own protective gear. It's not always about looking like kitted-out CAG dudes there, sometimes it's more about the training aspect to it.
You'll get contact shots, and 5-10 feet is typical, if not a bit on the far side for some layouts for engagement distance.
There is a HUGE difference between a well tuned gun running 350 fps, and a stock gun running 350 fps. Trigger response, rps, acoustic resonance, reliability are some of the first things which come to mind.
That's got nothing to do with how hot it shoots. In all honesty, I want to pick up a stock TM gun just for TTAC, I miss the mp5 that I had. Honestly, it was more accurate, had an incredible ROF on semi, and never broke once while using it. It was a fucking laserbeam.
Just come out and try it, bring a pistol, that's all you really need there.